Electric circuit breaker



C. THUMIM ELEcTnIVc CIRCUIT BREAKER @fnac/Afa VALVE Filed July 17, 1940 July s, 1941.

Thumim by AMMH His Attorney.

Patented July 8, 194i 'l 2,248,593 l ELECTRIC cmUrr BREAKER Carl Thumm, Yeadon, Pa., assignor to General Electric Company, a. corporation o! New York Application July 17, 1940, 'serial No. 345,973

(ci. zoo-14s) 3 Claims.

My invention relates to electric circuit breakers and more particularly to circuit breakers of the fluid-operated fluid-blast type.

In many installations, it is desirable to obtain higher speed of opening of circuit breakers than has heretofore been possible. Circuit breakers have been designed which operate by spring pressure but, where high speed tripping is desired, the mass of the springs becomes an important factor both in the amount of energy delivered to the moving parts and the rate of such delivery. In order to deliver sufilcient energy, the springs must be heavy and, therefore, the inertia of the actual spring parts prevents any considerable amount of energy from being delivered by the spring in the very short interval of time of the order of which it is desirable to operate highspeed circuit breakers. Furthermore, mechanical complications arise where springs are used since means must be provided to charge the springs, latch them in place and finally release them at the proper instant. For this reason, the use of fluids under pressure, such as air, has been suggested to supply the operating force for causing relative movementr between the contacts of circuit breakers since, in this manner, a large amount of energy with negligible inertia may be supplied. v

Diiliculties have been encountered in circuit breakers employing a blast of fluid for arc-extinguishing purposes When it is desirable to use this source of fluid pressure for producing relative movement between the contacts, particularly with respect to obtaining consistently similar performance therefrom. In the first place, a relatively high pressure is desirable to produce the desired fluid blast for arc-extinguishing purposes and fluid under the same pressure is normally used to produce relative movement between the contacts. In the second place, there is an optimum and comparatively narrow range of l velocity and separation of contacts for interrupting the circuit eil'lciently. Since a very large amount of fluid must be suddenly released to obtain a satisfactory arc-extinguishing blast, a considerable and variable pressure reduction in the able when a'source of fluid pressure supplied the operating force by resorting to springs for providing the relatively invariable operating conditions. This, as has been mentioned above, however, due to increased inertia adversely affected the operating speed and in addition introduced mechanical complications. It would be desirable, therefore, to provide a fluid-operated circuit breaker of the fluid-blast type in which relatively invariable circuit-breaker opening operation is obtained.

Accordingly, it is an object of my invention to provide a fluid-operated circuit breaker of the huid-blast type overcoming the difficulties set forth above.

It is another object of my invention to provide a. fluid-operated circuit breaker of the duid-blast type in' which uniform opening operation of the circuit breaker is obtainable under al1 conditions.

Further objects and advantages of my invention will become apparent as the following de scription'proceeds and the Afeatures of novelty which characterize my invention will be pointed out with particularity in the claims annexedtc and forming a part of this specification.

My invention will be better understood from the followingdescription taken in connection with the` accompanying drawing in which the single figure thereof is a schematic diagram partly in section of a fluid-operated circuit breaker of the fluid-blast type embodying my invention.

For explanatory purposes, I have illustrated my invention as applied to a circuit breaker of the cross fluid-blast type, such as is disclosed and claimed in the joint application of David C. Prince, William K, Rankin, and Wilfred F. Skeats, Serial No. 303,126, flied November 6, 1939,

.and assigned to the same assignee as the present y application. It will, of course, be understood by .is connected to the line terminal I4 while the movable contact l2 is connected to the line terminal I5. Fixed contact Il is provided with spring-pressed contact fingers Ila and .longer arcing contact lingers Il' while movable contact I2 is provided with an arcing tip l2 so that,

when the contacts separate, an are occurs between arcing tips II and I2'. Immediately after separation of the contacts, one terminal of the arc is transferred by a blast of fluid, preferably air, issuing out of conduit I6 from contact fingers II' to the contact II" which is provided with a tip of arc-resistant metal. The fluid or gas blast from conduit I6 upon opening o! the breaker drives the arc into the arc chute I3 against the edges of a plurality of partitions I1 in the arc chute, which partitions are transverse to the arc gap and the ends of which extend close to the path of movement of the arcing tip I2' or the movable contact I2. The circuit breaker III, illustrated by way of example in order to describe my fluid-blast control means, is not my invention but is described and claimed in copending application, Serial No, 303,126, referred to above.

Any suitable means for producing relative movement between the contacts II and I2 of the circuit breaker I may be provided. In the single figure, I have disclosed an arrangement in which circuit breaker I0 is automatically operated by fluid pressure. Accordingly, I have shown a iiuid motor comprising a cylinder |81 with a piston I9 connected through a rod 20 to operate a lever 2| secured to the shaft 22. The shaft 22 has attached thereto an arm of insulating material 23 for operating the movable contact I2 of the circuit breaker. Although circuit breaker IU is described with respect to a single phase, it will, of course, be understood by those skilled in the art that it may just as well comprise a plurality of phases in which case a plurality of arms 23 would be provided for operating the movable contacts I2 of the various phases. The arm 23 is shown provided with a pin 24 operating the member 25 secured to the outer end of movable contact I2. Member 25 is arranged to slide on a pair of rods 26, only one of which is shown in the drawing since the other is obscured from view thereby. It will be apparent that, when the shaft 22 is rotated in a counterclockwise direction, the arm 23 will move the contact I2 to the open position of the circuit breaker III and that, when the shaft 22 is rotated in a clockwise direction, the arm 23 will move the contact I2 to the closed position. The member 25 and the rods 26 constitute a kind of cross-head arrangement by which the movable contact I2 is reciprocated. This type of operating mechanism'is described in detail in United States Letters Patent 2,218,- '797, granted October 22, 1940, upon the joint application of Leonard J. Linde and Torild Andersen, and assigned to the same assignee as the present application.

Any suitable means for producing uid under pressure for supplying the uid blast for arcextinguishing purposes as well as for operating the circuit-breaker mechanism may be provided. In the drawing, I have illustrated schematically a suitable compressor 2l for compressing the duid which may be stored at a suitably high pressure in storage vessel 28. Storage vessel 28 is connected through a suitable reducing valve 2l to fluid-blast pressure reservoir 20 which is maintained at a relatively high pressure of the order of 150 pounds per square inch so as to supply the required iluid blast for arc-extinguishing purposes. Fluid-blast reservoir 30 is preferably connected through a suitable blast valve 3l to conduit I6 so as to supply a blast of nuid, preferably air, adjacent contacts I I and I2 of circuit breaker I0 for arc-extinguishing purposes. Blast valve 2l is normally biased to the closed position by means of spring 22 and is operated by means of solenoid 23 which may be energized at the desired time by any suitable control circuit.

In order to provide a fluid at a relatively low pressure'which is maintained substantially constant at all times so that consistent circuitbreaker opening speeds may be obtained, I provide a uid reservoir I4 connected to fluid-blast reservoir 30 through reducing valve 25. Valve 2i is arranged to maintain the pressure in fluid reservoir 34 far below that in reservoir l0 so that. when blast valve II is opened and a considerable pressure reduction occurs in reservoir 30, the pressure in reservoir 34 will be unatlected.` By this arrangement consistent operation of the relatively movable contacts is obtained while using a single pressure producing means.

Fluid reservoir 34 is connected with the respective ends of cylinder Il for operating circuit breaker III through a four-way control valve 36. This valve is arranged to control the closing of circuit breaker I0 by connecting reservoir. 34 with the right-hand end of cylinderV Il through conduit 31. For opening the circuit breaker on the other hand, valve 36 is adapted to interconnect reservoir 24 with the left-hand end of cylinder I8 through conduit 2li. Valve I6 is also constructed so as to vent one end 'of cylinder Il to atmosphere through conduit l! whenever the other end of cylinder I8 is subjected to pressure from low pressure reservoir I4. A suitable spring means 40 is provided to bias valve I6 to the closed position shown in the drawing. Valve Il is arranged to be operated for opening circuit breaker I0 by means of an opening solenoid 4I which may be energizedfrom any suitable control circuit. Similarly, valve 36 is arranged to be operated to control the closing of circuit breaker II by means of a closing solenoid 42 which may also be energized from any suitable control circuit. Blast valve solenoid 33, opening solenoid 4I, and closing solenoid 42`are preferably controlled in the manner disclosed and claimed in copending application Serial No. 310,599 of Bryce W. Wyman, led December 22, 1939, and assigned to the same assignee as the present application.

In view of the detailed description set iorth above, the operation of my new and improved fluid-operated fluid-blast circuit breaker will be obvious to those skilled in the art. A single compressor 21 produces the necessary fluid pressure and, by virtue of the separate low pressure reservoir 24, the reduction of pressure in blast reservoir 30 upon opening ot blast valve II will cause no effect in reservoir 24 since the pressure therein is considerably lower than the pressure to which reservoir 2l is reduced after blast valve II has been opened. By this arrangement, therefore, consistent opening speeds of the circuit breaker are obtained similar to those obtainable when using the spring arrangements mentioned above while, at the same time, dispensing with the high inertia factor tending to cause slower operating speeds.

It will be understood by those skilled in the art that reducing valve Il could be connected directly to storage vessel 2l since the pressure therein is always at least as high as that in blast reservoir 3l.

While I have shown and described a particular embodiment of my invention as applied to an electric circuit breaker, it will be obvious to those skilled in the art that various changes and modi-V fications may be made without departing from my invention in its broader aspects and I, therefore, aim in the appended claims to cover all such changes and modications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an electric circuit breaker, a pairot relatively movable contacts separable to draw an arc therebetween, a fluid motor for producing relative movement between said contacts, a high pressure source of fluid, means for introducing a, blast of said high pressure iluid adjacent said contacts for arc-extinguishing purposes, a 'low pressure source of fluid supplied from said high pressure source, said low pressure source being maintained at a suiciently low pressure so as to be unaffected by pressure changes in said high pressure source upon operation of said first-mentioned means, and means for operating said fluid motor from said low pressure source to produce relative movement between said contacts.

2. In an electric circuit breaker. a pair of relatively movable contacts separable to draw an arc therebetween, a source of fluid under pressure, means for introducing a blast of iluid from said source adjacent said contacts for arc-extinguishing purposes, a fluid motor, a second source of fluid under pressure connected to supply only said fluid motor, means for operating said motor from said second source to produce relative movement between said contacts, and means for maintaining the pressure of said second source independently of pressure changes in said iirst-mentioned source so that consistent operation of said motor may be obtained at all times.

3. In an electric circuitbreaker, a pair of relatively -movable contacts separable to draw an arc therebetween', a high pressure source of gas, means including a blast valve for controlling the introduction of a blast of gas from said source adjacent said contacts for arc-extinguishing purposes, a low pressure source of gas, means for maintaining the pressure of said low-pressure source independently of pressure changes in said high pressure source, a iiuid motor, means for operating said motor from said low pressure source to produce relative movement between said contacts, said low pressure source being arranged to supply only said iiuid motor so that consistent mechanical operation of said circuit breaker may be obtained independently of pressure variations caused by operation of said blast valve.

CARL THUMIM. 

